Horological time display



Nov. 17, 1970 N. c. zATsKY ETAL 3,540,209

HOROLOGICAL TIME DISPLAY I Filed June 12, 1969 3 sheets-sheet s FIG. 8

FIG. 9

FIG. IO

IN VENTORS Nov. 17, 1970 N, C, zATsKY ETAL 3,540,209

HOROLOGICAL TIME DISPLAY Filed Junelz, 1969 3 sheets-sheet 2 NVVENTORS/VRMAN C. ZATSKV EUGENE RKEELEP NOV. 17, 1970 N, Q ZATSKY ET AL3,540,209

HOROLOGICAL TIME DISPLAY Filed June l2. 1969 3 Sheets-Sheet l d ze P7FIGAf INVENTORS NORMAN C. ZA TSKY EUGENE l?. KEELER United States PatentO 3,540,209 HOROLOGICAL TIME DISPLAY Norman C. Zatsky, Briarcliil Manor,and Eugene R.

Keeler, Sulern, N.Y., assignors to Timex Corporation, Waterbury, Conn.,a corporation of Connecticut Continuation-impart of application Ser. No.749,607, July 31, 1968. This application June 12, 1969, Ser. No. 834,237

Int. Cl. G04b 1]/00 U.S. Cl. 58-50 15 Claims ABSTRACT OF THE DISCLOSUREAn electronic watch includes, within a case, a battery, a time base suchas a crystal oscillator, a series of countdown circuits, and a timedisplay. The time display includes a transparent watch crystal, a dialplate, and a liquid electro-optical material between the crystal and thedial plate. The crystal or the dial plate, or both, have a plurality ofconductive transparent lines. The lines are electrically triggered insequence to provide a moving indication of the time which appearssimilar to moving hands. The time display may provide a number of theAND circuits used in decoding, in addition to displaying the time.Alternatively, the time display may utilize a ferroelectric ceramicmaterial.

DESCRIPTION This application is a continuation-in-part of the applicantsnow abandoned U.S. application Ser. No. 749,007, filed July 31, 1968,and entitled Horological Time Display.

The present invention relates to horology and more particularly to thetime display of an electronic watch.

Many types of electric Watches, in which a battery within the Watch casedrives a motor, have been suggested and a few types have been placed incommercial production. It has been suggested that the motor simply windup the spring of a conventional mainspring driven watch. But this typeof a watch would be bulky, use a considerable amount of power and not beany more accurate than a spring-driven watch. Watches have been built inwhich the balance wheel acts as the armature of the motor; for example,the balance Wheel may carry a coil or a magnet. The balance wheel drivesthe gears of the Watch either directly or by means of a fork mechanisn.A watch in which the time base is a balance wheel inherently haslimitations due to the relatively low rate of the balance Wheeloscillation and to position error.

An electronic watch has been produced using a tuning fork as its timebase. Other types of vibrators have also been suggested as the time basefor a watch. However, it is still necessary in those watches for thevibrator to mechanically operate an index wheel, which requires adelicate and expensive mechanism. All these types of watches utilizephysically rotating hands to indicate the time. Fully electronicWatches, using a crystal or vibrator time base, have been suggested inwhich the time display, in place of rotating hands, would be a series oflamps or lamp-like devices, or a numerical display. In a numericaldisplay, one oclock is shown as 1:00. However, the high powerconsumption and cost of lamps and lamp-like devices has made suchsuggestions impractical. In addition, numerical displays are not desiredin a Watch by the consuming public.

It is an objective of the present invention to provide a portable watchwhich is wholly electronic, i.e., without any moving parts, and whichuses means other than physically rotating hands to display the time.

It is a further objective of the present invention to provide anelectronic time display which appears to rotate around a dial and whichdoes not display changing numerals.

It is a further objective of the present invention to provide anelectronic Watch having an electrically operated time display which islow in power consumption.

It is a further objective of the present invention to provide anelectronic watch which utilizes relatively few active elements fordecoding.

In accordance with the present invention, an electronic watch isprovided having a crystal, a dial plate, and a time base, such as acrystal oscillator or a vibrator. A number of count-down dividingcircuits re connected in tandem to the time base. A decoding systemconverts the binary code produced by the count-down circuits into a timedisplay.

-In one embodiment, the time display consists of sixty conductive radiallines evenly spaced on the back of the crystal or on the face of thedial. The crystal is spaced from the dial a short distance and the spacefilled with a suitable liquid crystal material. The time display may beconstructed with a set of such conductive lines shadowing a set ofconductive segments on the opposite surface of the thin layer of liquidcrystal material. The lines and segments are, in effect, two input ANDcircuits and may be used, in place of other active elements, in thedecoding system.

In another embodiment, a thin plate of a suitable ferroelectric ceramicis used as the dial. The ferroelectric plate is normally onlytranslucent but become transparent in selected discrete areas whenelectric fields are applied in those areas. The ferroelectric platecovers a colored or mirrored backing. The elds are applied bytransparent conductive lines on one side or both sides of the plate. Theplate becomes transparent in lines, revealing the backing material; and,as the electric iield areas change, the lines change, giving theimpression of moving hands. One embodiment of ferroelectric display mayalso be used in the decoding system.

Other objectives of the present invention will be apparent from thedescription of a preferred embodiment of the invention, taken inconjunction with the accompanying drawings, in which:

FIG. l is a top plan view of the Wrist watch of the present inventionwith its crystal and dial partly broken away to show its internalmechanism;

FIGS. 2, 3, 4, 5, 6 and 7 are top plan views of alternative dialsutilized in the wrist watch of the present invention; and

FIGS. 8 and 9 are side cross-sectional views of dial plates offerroelectric ceramic material.

As shown in FIG. l, the watch of the present invention is shown as beinga wrist watch having the external shape and approximate size ofconventional spring-driven wrist Watches. The time display of thepresent invention is not, however, limited to such wrist watches but maybe utilized in pocket watches, clocks and other horological instruments.

The wrist watch of FIG. 1 includes a one-piece case 10 having a unitarybezel portion '11. A transparent crystal |12 closes the case, which maybe made waterproof. A dial plate 13 is positioned beneath the crystal 12and spaced a short distance from it. A small electric battery cell 14,within the case 10, has one of its contacts grounded to the case. Forgreater power, additional cells may be utilized within the case. Thesecond contact 15 of cell 14 is connected to a terminal of theelectronic circuit 16.

The electronic circuit 16 includes a time base 17 which preferably is apiezoelectric crystal in a self-oscillatory circuit. Alternatievly, avibrator, for example, of the type disclosed in Sparings U.S. Pat.3,201,932, may be used as the time base. The time base 17 is connectedto a series of count-down circuits 18, 19 and 20, only three of whichare illustrated. A suitable count-down circuit is a lowpower consumingflip-flop counting circuit which counts down (divides) by two. Theflip-flop circuits are connected in tandem as a counter to provide anelectrical output at a predetermined rate. For example, to obtain outputpulses at the normal rates of 1 second, 1 minute and l hour, apiezoelectric crystal of 32.768 may be used. The crystal, which is partof a self-oscillatory circuit, has a pulse output rate of 32.768 kHz.The output of the crystal oscillator is connected to fifteen binarydivider circuits in tandem, yielding an output of l pulse per second.This output may be connected to ring counters to display seconds,minutes and hours. Preferably the piezoelectric crystal is small, so asto consume little power, and the flip-flops and other circuits areintegrated circuits.

The rst embodiment of the time display is shown in FIG. 2. 'In thisembodiment the dial plate is electrically conductive and connected toone terminal of the battery. The dial has printed thereon a set ofnumerals 21 or other time indicating marks. The dial has an outer ring22 and an inner circle 23 which are preferably of a roughened or sandblasted appearance. The crystal has sixty evenly spaced thin lines whichare used to indicate seconds. These lines are radially aligned andprinted in conductive transparent material, such as tin oxide, on theback (inner) face of the crystal. These sixty lines, which excited bythe electronic display counter one after another clockwise in sequence,cause a liquid crystal material to become reflective to light. One ofthese sixty lines 24 is shown as being triggered and becoming visible.

A second series of sixty evenly spaced similar transparent andconductive lines 25, on the back of the crystal, indicates minutes andhours. These lines 25 are thicker than the thin seconds lines 24. Asshown in FIG. 4, each of these thicker lines 25 consists, upon closeexamination, of two non-connected segments. The first segment 26 isclose to the inner circle 23 and the second segment 27 is close to theouter ring 22. The first segment 26 is separated by a smallnon-conductive gap 28 from the second segment 27. The rst segment 26 andthe second segment 27 have connected leads, respectively, leads `29' and30. As shown in FIG. 2, the minute hand 31 is formed by triggering bothsegments, so that the line is visible from the inner circle to the ring.The hour hand 32 is illuminated when the first segment is triggered.

The dial plate and the crystal are separated by a small uniform space,for example, .01 millimeter. The space between the dial plate and thecrystal is filled with a liquid crystal which changes its opticalproperties when a Voltage gradient is placed across the material. Forexample, the liquid crystal material may be an organic thermotropicnematic molecular material which changes from a clear liquid to a liquidwhich scatters light when positioned between charged plates, such as6-methoxy-2-naphthoic acid. This is a change from a clear to a frostedappearance when a voltage difference is applied to the plates betweenwhich the liquid is positioned. The liquid crystal may alternativelychange color. The transparent conductive lines may be very line forexample, 400 lines per inch, as the optical change in the liquid crystalhas sharp boundaries.

The second embodiment of the present invention is shown in FIG. 3. As inthe previous embodiment, the entire dial is conductive and connected toa battery terminal. The dial has a series, of number 33 printed on itsface, indicating time. The dial has three separating rings-an outsidering 34, a rst inner ring 35, a second inner ring 36 and a centralportion 37, all of which may be colored or patterned for decorativepurposes. The crystal has three thin rings, each of which is formed of60 short segments of transparent conductive material on the inner (back)side of the crystal. The outer ring 38 represents minutes, the centerring 39 represents hours, and the inner ring 40 represents seconds. Thedial plate directly under each of the rings 38, 39 and 40 is black. Thesegments of all of the rings 38, 39 and 40 are electrically excited,except for one segment in each ring. The one untriggered segment in eachring is clear (not opaque) and permits the black marks 41, 42 and 43 toshow through, indicating time. All the other segments are triggered andcause the liquid crystal material directly beneath the segment to beopaque and to hide the black marks.

The consumption is directly proportional to the area charged.Consequently, the narrow bands utilize relatively little power, although59/ 60 of the bands are always charged.

To help distinguish the seconds indication from the other timeindications, the second indication may be liashed with on-off periods ata visible rate, such as ten cycles per second. As another example of apossible modiication, in the embodiment of FIG. 2 the liquid crystalmaterial need only occupy a closed space, considered in the plan view,formed between the inner circle and the outer ring. As still anotherexample of a modification, the transparent conductive lines may beprinted 0n a separate clear sheet positioned behind the crystal andabove the dial, the liquid crystal material being positioned between thedial and the clear sheet.

Another embodiment of the invention is shown in FIG. S. The dial 12 orthe crystal 13 carries permanent markings in the form of numerals and/or lines in the zone of an outer ring 45, similar to the embodiment ofFIG. 2. This zone `45 has a roughened or sandblasted appearance. Theannular zone between the outer ring 45 and the center circle 23 is usedfor the display of time which appears to move. There are sixty evenlyspaced lines 46 which are used to indicate both minutes and seconds. Anyparticular one of the lines y46 remains energized for one minute. At theend of one minute, the next line 46 of the sequence is energized for aminute. During the one-minute interval, successive lines of the sixtylines are flashed for a small fraction of a second at one-secondintervals, giving the impression of a sweep second hand.

As shown in FIG. 5, a set of twenty-four evenly spaced lines 47 aresomewhat shorter and heavier than the rst set of lines 46. Every otherone of these lines 47, such as line 47a, is closely adjacent to a line46 of the first set which coincides with the position of the hour handof a conventional watch at the full hour. The remaining twelve lines4711 occupy the position of the hour hand of a conventional watch at thehalf hour. Each of these twentyfour lines `47 is energized for one-halfhour, after which the next line of the set 47 is energized in clockwisesequence. The iirst mentioned twelve lines 47a are energized (one at atime) from 15 minutes before the full hour to l5 minutes after the fullhour, the second group 4711 is energized from l5 minutes after the hourto l5 minutes before the next hour. This arrangement resolves anyambiguity which might occur if only twelve lines were used for the hourdisplay, such as mistaking an indication of 12:58 for 11:58.

'In the embodiments of FIGS. 6 and 7, the number of necessary activeelements, such as transistors, is reduced by using the time display toperform two functions. The time display is used for its normal functionof indicating time. In addition, the display elements are used as doubleinput gate AND circuits to decode the output of the countdown circuits.

The seconds display counter described in connection with FIGS. 6 and 7of this invention has sixty separate and distinct output states Iwhichmust be decoded from a 6-bit binary code to a one out of 60 code todrive the 60 seconds indicators. A binary code may use a 0 or l in eachposition so that a six-bit binary code may be 010011. The combinationsof zero and one using six bits are 26 or 64. The binary code is producedby the tandum series of count-down circuits. The decoding isaccomplished, using digital techniques, by utilizing a series of logicalgates. The required conversion could be done using 60 six-input ANDgates, but this is wasteful of circuitry requiring 360 (6x60) activedevices.

'Each of the sixty AND gates would have six inputs. The AND gate wouldoperate only when pulsed with the particular binary code for that gate.For example, the six-bit code 010011 will operate the one out of thesixty AND gates which is pre-cooled to produce an output when that codeappeared in that order and simultaneously at its six input gates.

Another method of decoding, which is more economical from a point ofView of hardware, uses what is known as two-level gating. In two-levelgating the six-bit binary code is split in half. The three mostsignificant bits are decoded to a one out of eight code using eight ANDgate circuits each having three inputs and the three least significantbits are also decoded to a one out of eight code. The outputs of each ofthe first group of eight gates with the outputs of the second group ofeight gates, via 46.0 AND circuits, each having two inputs, yield therequired 1 out of 60 format. This method uses only 168(2X60-l-3X8-l-3X8) active devices.

It is possible to lower the count of active devices required fordecoding by using the display element as part of the decoding matrix asshown in FIG. 6. For this approach the sixty transparent and conductivelines are deposited on the back face of the transparent watch crystal 12as before. The dial 1%` has a pattern of eight annular segments S057formed of a conductive material which may also be transparent. Seven ofthe segments 50-56 each mask 8 lines of the top plate, the eighthsegment 56 masking four lines. The sixty top radially aligned lines 60are electrically connected in the following manner, counting each of thesixty lines in sequence:

The dash between the numbered lines, above, indicates an electricalconnection between them. As in two level gating, the -6Lbit counter issplit in half and the three most significant bits are decoded yusingeight AND circuits each having three inputs. The outputs of thesecircuits are designated A11, A2, A3, A4, A5, A6, A7, A8. The leastsignificant bits are decoded in like manner and the outputs of theircircuits are designated B1, B2, B3, B4, B5, B6, B7, BS. A1 is connectedto a switch which, when activated, connects a voltage source V1 to thefirst annular segment 50. A2 through A3 drive the remaining annularsegments 51-56 in like manner. B1 is connected to a switch which, whenactivated, connects a voltage source V2 to line segment 1. B2 throughB18 drive line segments 2 through 8 in similar fashtion.

With the counter in position zero, A1 and B1 are both ON and linesegment 1 is activated. After one second, B1 turns OFF and B2 turns ON,activating line segment 2. After eight seconds, B8 turns OFF, recyclingthe decoder to B1 while A1 turns OFF and A2 turns ON This combinationenergizes line segment 9. In this manner all 60 line segments areactivated sequentially with only 48 (3X8-i-3X8) active decodingelements. The liquid crystal is optically affected only when a voltageis placed across it, i.e., when there is a Voltage difference between asegment and a line. In effect, the liquid crystal, segments and linesact as two-input AND circuits. In a two-input AND circuit, both gatesmust be activated simultaneously for there to be an output. The segmentmay be considered one input and the line, the other input and theoptical response the output.

This method becomes even more attractive if the back watch platecomprises two concentric segmented rings 70 and 71, as shown in FIG. 7.Herein data from the hours counter is presented to the 60 line segmentson pulsed basis at a 50% duty cycle. When the hours date is beingdisplayed, only the inner concentric ring is energized, so that thedisplay is a short line segment. During the other half of the time, datafrom the minutes counter is displayed with both rings energized. Thisdisplays a longer line segment.

If the information is pulsed rapidly (greater than 30 times per second)the human eye tends to integrate the flickering so that the displayappears not to blink.

An alternative construction to the liquid crystal cell is a solidferroelectric electro-optically active ceramic plate. This material is apolycrylstalline ferroelectric ceramic. A preferred material is a hotpressed rhombohedral lead zirconate-lead titanate ceramic. The ceramicis pressed into a thin plate and polished.

As a specific example, the material may tbe a solid solution containingabout 64% lead zirconate, 34% lead titanate, and 2% bismuth oxide. Thesolution is pressed for one hour at 3000 p.s.i. and at 1300 C.

Preferably, as shown in FIG. 8, the dial plate of a `watch consists of athin ferroelectric ceramic plate 8'1, for example, a thickness in therange of .1 mm. to .01 mm., mounted on a non-conductive colored ormirrored backing material 82, for example, of a compatible ceramicmaterial. A thin transpartent layer of conductive material 83, havingthe desired pattern, is sandwiched between the ferroelectric ceramic andthe backing material. A second thin transparent conductive layer 84a and84b, which may or may not have a pattern, is adhered to the top surfaceof the ferroelectric ceramic. As shown in FIG. 8, a voltage field isapplied across 8417 and 83, switching the area between them to a uniformparallel polarization and causing it to 'become transparent. That area,which may, for example, be a seconds indication, will become transparentand permit the color or mirror of the backing material 82 to be seen.

As shown in FIG. 9, a dial plate consists of a thin normally transparentferroelectric ceramic plate 91 mounted on a colored or mirrored rigidnon-conductive backing material 92. The plate is poled, in its course ofmanufacture, in a D.C. field and, after removal of that field, stillretains its polarization. A thin transparent conductive line pattern 94aand 94b, having the desired pattern, is adhered to the top surface ofthe ferroelectric ceramic. As shown in FIG. 9, a voltage field isapplied between lines 94a and 94h, switching the area between them to adifferent polarization and causing that area to scatter incident light.That area is an indication of time, for example, an hour hand position.The area `93 between the conductive lines 94a and r94b, when it becomesfrosted (scatters light) does not permit the backing material to showthrough.

The decoding pattern described in connection with FIG. 6 may be usedwith the ceramic structure of FIG. 8. The other patterns of FIGS. 2, 3,4, 5 and 7 may be used with the ceramic structure of either FIG. 8 orFIG. 9. The pattern may be placed on the front face or the rear face ofthe ceramic plate, or on both of its faces.

It is desirable, in the structure of FIG. 9, that the space between theconductive lines be as narrow as possible so that lower voltages may beused. As shown in the top plan View of FIG. l0, the conductive line liesin an interdigital pattern with the conductive line 101 forming a smallgap 102 between them. The gap 102 becomes transparent with a voltage isapplied between lines 100 and 101. The gap 102 is preferably only a fewmils wide. A line appears, when the gap is viewed from a littledistance, which appears to be almost a solid line running in thedirection of arrow 103'.

We claim:

1. An electronic horological device including a case, a source ofelectrical power, a time base, an electronic circuit, a dial plate, acrystal, and a. time display, wherein the time display includes a liquidcrystal material behind the face of the crystal, a plurality ofconductive transparent lines on said crystal and a plurality ofconductive arcas on said dial, said lines and said areas ibeingpositioned to create a voltage gradient across the liquid crystalmaterial and triggered in sequence by said electronic circuit, saidlines being radially aligned relative to the center of said dial.

2. A horological device as in claim 1 wherein the horological device isa wrist watch and the source of electrical power is a battery celliwithin said case.

3. A horological device as in -claim 1 wherein the time base is acrystal oscillatory circuit and the electronic circuit includes a seriesof count-down dividing circuits.

4. A horological device as in claim 1 wherein the liquid crystal is anorganic mematic material.

5. A horological device as in claim 1 wherein the said lines are formedinto a rst group of sixty evenly spaced and radial lines and a secondgroup of sixty evenly spaced radial lines.

6. A horological device as in claim 5 wherein each of the linesconstituting the said second group of lines consists of a rst segment, asecond segment, and a gap between the segments, and wherein the saidsegments each have separate connection lines.

7. A horological device as in claim 1 wherein the transparent lines formthree concentric rings, with each ring consisting of sixty segmentsseparated by gaps, each segment having an independent connecting lead.

'8. A horological device as in claim 1 wherein the said transparentlines are on the underside of the watch crystal and the liquid crystalmaterial is positioned between the crystal and the dial.

9. A horological device as in claim 1 wherein the time display comprisesa set of conductive lines and a set of conductive segments which shadowthe said lines, the said lines and segments constituting two-input gatecircuits utilized for decoding.

10. An electronic horological device including a case, a source ofelectrical power, a time base, an electronic circuit, a system, a dialplate, a crystal and an electro-optic material, wherein the crystal anddial plate constitute iirst and second display substrates, one of thesaid substrates having a plurality of conductive lines and the otherhaving a plurality of conductive areas, the electro-optic material beingpositioned between the said lines and the said areas, and the lines andareas being positioned to create a voltage gradient in the electro-opticmaterial.

11. An electronic horological device including a case, a source ofelectrical power, a time base, an electronic circuit, a dial plate, acrystal, and a time display, wherein the time display includes anelectro-optical ferroelectric ceramic material behind the face of thecrystal and visible through said crystal, a plurality of conductivetransparent lines positioned on said crystal and a plurality ofconductive areas positioned on said dial to create a voltage gradient inthe ceramic material and triggered in sequence by said electroniccircuit, said lines being radially aligned relative to the center ofsaid dial.

12. A horological device as in claim 11 wherein the horological deviceis a wrist watch and the source of electrical power is a battery cellwithin said case.

13. A horological device as in claim 12 wherein the time base is acrystal oscillatory circuit andthe electronic circuit includes a seriesof count-down dividing circuits.

14. A horological device as in clai-m 12 wherein the ceramic material isa hot pressed lead zirconate titanate solid mixture in the form of theplate in the order of one mil thick.

15. A horological device as in claim 12 wherein the ceramic material isa thin polished plate in the order of one mil thick mounted on a coloredor mirrored rigid backing plate.

References Cited UNITED STATES PATENTS 4/1969 French 340-173 l2/1969Langley 1 58-50 X U.S. Cl. X.R. 340--

